In a two-cycle internal combustion engine, as the piston moves upward from bottom-dead-center, the intake phase begins. Air travels through the air filter and the air intake boot and is mixed with fuel in the carburetor. The combustion mixture of air and fuel travels through the intake manifold and the reed valve, into the crankcase of the engine. When the piston moves downward from top-dead-center, it displaces the combustion mixture in the crankcase thus ending the intake phase and starting the combustion phase.
Due to the inertia of the incoming combustion mixture, which is still moving through the intake system when the reed valve closes at the end of the intake phase, a back pressure and reversal of flow of the combustion mixture causes a pressure rise at the carburetor. This rise in pressure at the carburetor results in a change to the mixing ratio of fuel-to-air producing a "rich" condition which causes a decrease in performance of the engine by causing a hesitation in acceleration (flat spot) which is very noticeable at low engine R.P.M. Additionally, the efficiency of the engine is also decreased because the ratio of fuel-to-air is too high, resulting in wasted fuel.
In the present state of the art, this undesirable back pressure and reversal of flow (backflow) is reduced by various inventions which incorporate some form of an auxillary chamber commonly referred to as a surge chamber or pressure chamber. This auxillary chamber is connected to the intake manifold between the carburetor and the reed valve and is used as a holding chamber to hold the backflow gasses until the reed valve opens and the next intake phase begins. This solution greatly reduces the back pressure at the carburetor, but it also significantly increases the volume of the intake manifold. This significant increase in volume of the intake manifold itself creates a detrimental effect on the engine's performance which is very noticeable at high engine R.P.M.
Accordingly, an object of the present invention is to improve the performance of a two-cycle internal combustion engine by eliminating or greatly reducing the undesirable backflow of combustion mixture through the intake system.
Another object of the present invention is to eliminate or greatly reduce this undesirable backflow of combustion mixture through the intake system without significantly increasing the volume of the intake manifold, as is common in the present state of the art inventions.
Still another object of the present invention is to increase the efficiency of a two-cycle internal combustion engine by reintroducing the backflow combustion mixture gasses back into the intake system ahead of the carburetor so that the gasses may be merged with the incoming air stream and remixed in the carburetor.
In the present invention, the objects mentioned above are accomplished by the insertion of a flow pickup into the intake manifold ahead of the reed valve which captures and directs the backflow combustion mixture gasses through a primary passageway, through a uni-directional control valve, through a secondary passageway, and through a flow injector, which reintroduces the backflow combustion mixture gasses back into the intake system ahead of the carburetor where the backflow gasses can merge with the incoming air stream entering the carburetor.
The length of this recirculation travel tube assembly is extremely critical to the engine performance and determines its frequency of operation. The frequency of operation of this invention must match the frequency of the engine's flat spot (hesitation in acceleration point). Each engine has a different frequency of operation and the present invention must be modified in length (tuned) to insure that its frequency of operation matches the frequency of operation of the engine.
When the present invention has been installed and tuned to match the engine's frequency, the length of time that the combustion mixture backflow gasses take to travel through the invention will be equal to the time it takes the piston to complete its combustion phase and begin a new intake phase. Thus the amount of backflow combustion mixture gasses present to interfere with the proper mixing of fuel-to-air by the carburetor is greatly reduced or eliminated completely. The result when the present invention is properly tuned to the engine's frequency is a smooth power transfer without any hesitation in acceleration (flat spot) at low engine R.P.M., and a more efficient performance.